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Re: Theropod hunting strategies



The following is from a message posted by rowe@lepomis.psych.upenn.edu
(Mickey Rowe) for Thomas_R_HOLTZ@umail.umd.edu:

<< 3) Pursuit-and-bite.  Typified today by canids (dogs, wolves, etc.),
  hyaenids, the cheetah, and in the recent past by flightless
  predatory birds.... Pursuit-and-bite predators
  characteristically run down their prey after a fairly long chase,
  seize the prey in their jaws, and kill the prey with a combination
  of biting and suffocation.  The claws, if used at all, are used to
  stabilize the victim so the jaws can do their work.>>

I think it worth noting that cheetahs do not bring down their prey by seizing
it with their jaws.  Rather, they possess a modified "dew claw" (the
thumb-claw, that is) on their front feet (all the other claws have lost their
protractile nature and became very dog-like). To bring down prey, the cheetah
swats at it with one of its forefeet, snagging the skin with this claw.  This
effectively "trips" its prey, whereupon after a short grapple, the cheetah
kills with a bite to the neck (either by crushing the throat or severing the
spinal cord).
In this light, the cheetah is probably more of a "Grapple-and-Slash"
predator, even though it certainly persues its prey!

<< Dromaeosaurids are
  excellent candidates for grapple-and-slash predators, since they
  proportionately short and stout legs (forget ever reference you've
  seen to Velociraptor and Deinonychus as being "swift" as dinosaurs
  go.  Even Tyrannosaurus rex has proportionately longer lower legs
  and feet than do these smaller forms).>>

I have often noted that Deinonychus had rather heavily-built calves (in the
restorations I have seen, anyway) for an animal its size.  This would
indicate a great deal of leg-power, which seems reasonable, given that its
most famous weapon was a toe!  This would also indicate that Deinonychus was
probably more of an accelerator than a speedster.  My guess is, though I
haven't seen many REAL Velociraptor restorations, that they were similar.  So
much for Velociraptor being "speedy", eh?  

<< Tyrannosaurids fit well with the pursuit-and-bite catagory.  Like
  canids and hyaenids, they have proportionately long legs (T. rex
  itself has legs which are more "cursorial" than the man-sized
  herbivore Dryosaurus and other accepted runners), very powerful
  jaws, and claws of the hand and feet which are not highly curved and
  rounded in cross-section.  Although they may not have pursued prey
  for wolf-like distances, the body of anatomical evidence points to
  the adaptations of tyrannosaurids as being predatory, and
  specifically pursuit-and-bite predatory, features.>>

Particularly since the other two categories seem to involve the use of
forelimbs! :o)>
The claws on the feet were more likely to be used for traction than for
killing, thus their rounded nature.  Allosaur toe claws, on the other hand,
are very similar to the killer claws of dromaeosaurs (and about as large!).
 Allosaurs may not have been above taking a foot-swipe at its prey once it
had been downed, or at least stopped.

<< His claim that predators need to use their forelimbs in
  prey acquisition does not stand the test of observations of the
  modern world.  Tyrannosaurids show more cursorial adaptations than
  any other large Late Cretaceous Asiamerican dinosaur (hadrosaurids,
  ceratopsids, ankylosaurids, etc.), so they probably were faster than
  any of these.>>

And those huge neck / jaw muscles may well have made the forelimbs redundant,
and therefore obsolete.  Rather than grapple with its prey, a tyrannosaur
merely had to catch up to it and take a (large) bite out of its hide. Then
wait for it to slow down enough from blood loss to move in and finish the job
with a few well-placed bites.  No grappling necessary!

Derek Smith